Originally Posted by CYF

It's not illegal to count cards. I've played in casinos before where the dealer and pit boss didn't give a shit, which was cool. Good dealers can count cards too, and they can usually tell if you're counting.

I was watching a table once, picking up the count, and all the players got up and left cuz they were losing left and right. Sat down by myself at the table and won 500 bucks the remainder of that shoe

You're right tho, I just checked my Beat the Dealer book, and with basic counting you have a .1% advantage over the house. 1.5 - 3% advantage if you can count cards also.